1. Field of the Invention
The present invention relates generally to an apparatus for producing an electrophotographic print on a photosensitive material, and more particularly, a wet-type electrophotographic copying machine including an improvement on the treatment of the used developer remaining on the photosensitive sheet.
2. Description of the Prior Art
In a wet-type electrophotographic copying machine, hereinafter referred to merely as the copying machine, it is necessary to remove the used developer remaining on the photosensitive sheet. To this end there have been many proposals, among which are methods disclosed in Japanese Patent Publications (examined) No. 51 (1976)-15747, and No. 58 (1983)-47707. Both of them teach the employment of a special roller kept in contact with the photosensitive sheet, thereby collecting the used developer, and returning it into the reservoir.
However, the developer is collected in the reservoir after it has flowed along the surfaces of the photosensitive sheet. In the course of flowing on the surfaces of the photosensitive sheet, the toner is consumed in conducting the expected development, and the developer as a whole is diluted. In addition, the developer unavoidably becomes contaminated by other substances which are mixed in. If the diluted, polluted, used developer enters the reservoir, the developer therein will be diluted and polluted. This deteriorates the developing ability, and shortens the life of the developer.
To compensate for the diluted developer, it becomes necessary to constantly give a fresh supply of developer. Particularly, in a multi-color copying machine it often happens that a developer for one color gets mixed with one for another color. This is fatal to color copying.